* All engines: Active voices are now internally grouped to "Note" objects,
instead of being directly assigned to a keyboard key. This allows more
fine graded processing of voices, which is i.e. required for certain
instrument script features.
* Built-in script function "play_note()": Added support for passing
special value -1 for "duration-us" argument, which will cause the
triggered note to be released once the original note was released.
* Bumped version (2.0.0.svn3).

* Introduced Signal Units and Signal Unit Racks, which hopefully will meet
the demands of the new engines for flexible signal processing.
* sf2: Initial implementation of vibrato LFO, fixes in modulation EG and
and volume EG (work in progress)

* implemented Roland GS NRPN 1ArrH which allows to set volume per note
* implemented Roland GS NRPN 1CrrH which allows to set pan per note
* implemented Roland GS NRPN 1DrrH which allows to set reverb send per
note (in this implementation of the sampler its simply hard routed to
the 1st effect send of the sampler channel, no matter what the actual
effect type is)
* implemented Roland GS NRPN 1ErrH which allows to set chorus send per
note (in this implementation of the sampler its simply hard routed to
the 2nd effect send of the sampler channel, no matter what the actual
effect type is)
* bumped version to 1.0.0cvs4

* VST bugfix: If the host called resume() before and after changing
sample rate or block size, the number of channels was incorrectly
set to two. This caused silence in Cubase 5.
* removed compiler warnings